An optical microscope is known from U.S. Pat. No. 7,345,816 B2 that comprises a mirror with a controllably variable reflective surface. By changing the surface of the mirror, images can be taken from different focal positions.
The product “3D Microscope” by the manufacturer SD Optics is used for the rapid generation of macroscopic and microscopic images having an extended depth of field (EDoF). In order to achieve the EDoF functionality, a mirror array lens system called a MALS module is used. MALS stands for Mirror Array Lens System. Details of this system are disclosed in WO 2005/119331 A1 or WO 2007/134264 A2, for example.
EP 2 687 890 A1 describes a device and a method for compressing stacks of microscopic images.
A method for improving the depth of field in microscopy is known from EP 2 687 893 A1. An image stack with different focus settings, which can also be called a z-stack, is captured as a sequence. The images of the stack are superimposed in order to obtain an image with an extended depth of focus.
DE 10 2014 006 717 A1 describes a method for generating three-dimensional information for an object in a digital microscope. In this method, an image is taken for each focus position and stored with the associated focus position in an image stack. An EDoF image is calculated from the acquired images of the image stack. During the process of calculating the EDoF image, a number of pixel defects are detected, which are corrected by interpolation with neighboring pixels. The corrected EDoF image is used to calculate a height map or 3D model of the object.
Taking the prior art as a point of departure, it is the object of the present invention to minimize the drawbacks of unadapted illumination of a specimen when acquiring a stack of microscopic images with different focus positions. Unadapted illumination leads to overexposed or underexposed regions in the individual acquired images that which are visible in the form of reflections or shadows in the image, for example. The stack of microscopic images taken from different focus positions is used to produce images with an extended depth of field or three-dimensional images.